Aryloxy Samarium (iii) Catalyzed ¦Å-caprolactone Ring - Opening Polymerization Activity And Quantum Chemistry Calculation Auxiliary

10 phenols specifically substituted by methyls, tertbutyls or octyl (1,1,3,3-tetramethylbutyl) at different site with different numbers were firstly chosen as ligands for Sm(III) phenolates, all of which were utilized as single component catalyst for ring-opening polymerization (ROP) of -caprolactone (CL).The experimental results turned out that, all phenolates' catalytic activities and ROP polymerization characteristics changed in good concordance with variation of substituents' site and numbers:1). With phenol (4M, 2M vs. P) singly substituted by methyl (especially ortho ones), the corresponding Sm(III) phenolates have higher catalytic activities and obtain PCL with higher weight average molecular weight (Mw) while wider molecular weight distribution (MWD): Sm(2M)3> Sm(4M)3 ? Sm(P)3.2). With phenol substituted by two methyls (24DM vs. 26DM): Sm(24DM)3, for which the ligand phenol was substituted by one methyl at ortho site and the other at para site, has higher catalytic activities and obtain PCL with higher Mw while wider MWD either than Sm(2M)3 or Sm(4M)3; Sm(26DM)3, for which the ligand phenol has two ortho methyls, has lower catalytic activities and obtain PCL with lower Mw while narrower MWD either than Sm(24DM)3 or Sm(2M)3, even Sm(4M)3. Therefore, for phenolates with methyl substituents, the order for catalytic activities as well as PCL's Mw and MWD was: Sm(24DM)3> Sm(2M)3 > Sm(4M)3> Sm(26DM)3> Sm(P)3.3). With phenol (4B, 2B vs. P; 2B4M vs. 4M) singly substituted by tertbutyls (especially ortho ones), the corresponding Sm(III) phenolates have higher catalytic activities and obtain PCL with higher Mw while wider MWD: Sm(2B)3> Sm(4B)3? Sm(P)3; Sm(2B4M)3> Sm(4M)3.4). With phenol (26B4M vs. 2B4M) substituted by two tertbutyls at ortho sites, Sm(26B4M)3 has the highest catalytic activity and obtain PCL with highest Mwwhile widest MWD: Sm(26B4M)3> Sm(2B4M)3> Sm(4M)3. 5). With phenol substituted by octyl (1,1,3,3-tetramethylbutyl) at para site (40), Sm(4O)3 has the lowest catalytic activity compared with Sm(4M)3 and Sm(4B)3.To clarify the correlation between phenol structure and phenolates' catalytic activities and ROP characteristics, we optimized all phenols' structures with quantum chemical (QC) calculation method and obtained geometric parameters and charge distribution data for them. The computational data concerning hydroxyl hydrogen (H*), oxygen (O7) and the phenyl carbon (C1) directly connected with hydroxyl, together with experimental data were discussed in organized groups in light of orderly change of substituents' site and size, trying to find out influence of substituents electronic and steric effects on phenolates' catalytic activities and ROP characteristics. It was found that:1). Methyls, especially ortho ones, induce longer C'-H* distance and more negative charge on O7, the former of which introduces more space around the metal center of phenolates and the latter induce increased nucleophilicity on O7. Both of them contribute to easier coordination and insertion of monomer, hence induce higher catalytic activities on phenolates. Besides the positive electronic effect, more space around the metal center of phenolates also induce more intermolecular transesterification reactions, so Sm(2M)3 obtain PCL with higher Mw while wider MWD.2). Two Ortho methyls decreased the space around the metal center of Sm(26DM)3 and induce obvious negative steric effect; Sm(26DM)3 therefore is much less active than either Sm(24DM)3 or Sm(2M)3, obtaining PCL with lower Mw but narrower MWD.3). Single tertbutyl, especially ortho one, induce mixed electronic effect but positive steric effect, the former of which doesn't result in increased or decreased catalytic activities while the latter contributes to increased catalytic activities for phenolates.4). Double ortho tertbutyls in 26B4M results in not only positive steric effect but also un-regular positive electronic effect, both of which induce much enlarged space around the metal center, thus contribute to much increased catalytic activity of Sm(26B4M)3 and intermolec...